1. Field of the Invention
The present invention relates generally to the magnetic recording of information signals and in particular to the recording of such signals on a magneto-optic medium.
2. Description Relative to the Prior Art
The use of magnetic heads to lay down and respond to records on a magnetic medium is well known and is undoubtedly the most frequently employed approach to magnetic recording/playback. The "magnetic-head record/playback approach" results, generally, in compact systems which are economical in relation to alternative approaches such as optical recording and playback. One disadvantage, however, is that mechanical requirements for the magnetic heads tend to work against reduction in head size beyond a certain range. For this reason, practical head sizes, generally, produce track widths which do not use to full advantage the resolving power of the magnetic recording medium (e.g., magnetic tape). A further source of difficulties is the limited ability of magnetic heads to play back very low frequencies. This problem results because playback using magnetic heads is an induced-voltage type of process and is strongly influenced by the magnetic flux change per unit time (d.phi.)/(dt). In fact, at low levels of d.phi./dt the induced signal may become so small as to be totally obscured by noise and for this reason such low frequency signal components are generally avoided in recording with magnetic heads.
Some optical record/playback systems have been developed which rely on Kerr, or on Faraday, magneto-optic effects and avoid the resolution and low frequency (such optical effects are not d.phi./dt dependent) problems of the magnetic head approach. Such optical systems, however, generally incorporate a powerful recording laser which, with associated drive electronics, is expensive and bulky. Also, the safety concerns with powerful lasers militate against their use in apparatus for the general consumer.